A couple of days ago zodern released version 1.5.11 of mup which fixes the above issue. And also an issue I had started having previously with ssh key auth on newer Ubuntu versions.
Just deployed a Meteor 3 project to a Ubuntu 24.04 server and the process went flawlessly.
Added a sponsorship to him as well on github. If you’d like to do so as well, here’s the link: Sponsor @zodern on GitHub Sponsors · GitHub